I live in Seattle, zone 8ish (maybe different as I'm in the foothills of the
mountains) and talking to a nursery owner about some perennials for a
filtered sun area he recommended potentially some helleborus plants.

I'm not at all familiar with this plant, he indicated that the flower was
spring only but that it wouldn't die back during the summer so the plant
itself would be green all season. He also suggested potentially some
primroses for fill in the gap cover. It was my understanding that primroses
will die back during the summer and tend to look shabby when not in bloom -
but they will reseed themselves and come back the next spring.

So I guess I'm wondering, what could I expect from a helleborus in a
filtered sun area and do they stay green year round? do they self
perpetuate or are they more like shrubs.